The invention relates to networks using existing telephone wiring, and, in particular, to filtering high frequency components from electrical signals transmitted along the network and passing low frequency components of the electrical signals to devices using POTS technology (Plain Old Telephone System).
For example, asymmetric digital subscriber line (ADSL) networks transmit electrical signals representing information along existing telephone wiring. The information is, for example, both high frequency digital signals, such as video from a service provider transmitting a pay-per-view movie to a customer or Internet data, and low frequency analog voice signals, such as the voices of a telephone call carried along the lines of the service provider. Both types of information, high frequency signals and low frequency signals, are combined as components of a single electrical signal.
ADSL networks transmit high frequency digital data asymmetrically. ADSL networks transmit data upstream from a subscriber node (e.g., a home or an office) to a provider node (e.g., a telephone company or an Internet service provider) at a slower rate than the networks transmit data downstream to the subscriber node. In addition, ADSL networks transmit analog voice signals at an even lower frequency than either the upstream or downstream data. In addition, both the upstream and downstream frequency ranges can contain several sub-bands or sub-channels that allow several sets of data to be transmitted in the same direction at the same time by using different frequencies within the respective ranges.
When electrical signals arrive at the subscriber node, the high and low frequency signal components are separated into separate electrical signals for use by an appropriate device such as a television, a personal computer, or a telephone set. To separate the signal into the various frequency components, hardware is installed at the subscriber node. For example, home wiring is broken and a POTS splitter is connected to the home wiring between the break. The POTS splitter separates the low frequency electrical signal components from the electrical signal and sends the low frequency component to the low frequency devices, such as a telephone set, along one wiring path while sending the high frequency component along another path. The POTS splitter sends the high frequency signal component to an ADSL modem and the low frequency signal component to the low frequency devices.
Current methods of adapting subscriber nodes, such as homes, to ADSL technology require changing existing hardware, e.g., inserting the POTS splitter requires changing the existing home wiring and providing additional wiring for the high frequency signal. However, one of the primary advantages of ADSL technology is that it utilizes the existing twisted pair wiring that already exists in most homes. Thus, methods of adapting subscriber nodes to ADSL technology, which require alterations to existing wiring at the subscriber node, reduce the advantages of providing services over an ADSL network.
As another example, future home phone network applications (home PNA) may also use existing telephone wiring within a home to create a local area network (LAN) within the home. While an ADSL network transmits high frequency components on the order of approximately 20 kHz to 1 MHz, residential LANs could transmit even high frequency components on the order of approximately 4 MHz to 10 MHz. As with ADSL technology, methods of adapting existing wiring for use in a residential LANs that require extensive modifications would decrease the advantages of utilizing existing wiring.